Many of the people you'll have to take down at the beginning of this level
are friendly. Make sure you have the Crossbow set to Sedate before starting.
You'll have to be stealthy to pull off the first part of this mission. Quickly
loop around the column to the left, dropping the guard here with a Crossbow
bolt.

There
are two more guards to sedate. Follow the one patrolling the path, then turn
to you left and get the guard camping in a nook just past the door. Your
aim will have to be true. There is an alarm near this guard, and if he gets
to it, all will be lost. Drop him, then, from the shelter of this cove, clean
up the guy on the path.

Now head to the tunnel to the left. The first person you'll encounter here
is the stewardess. Use the Crossbow to sedate her, then grab her uniform.
Put it on immediately.

Hidden Item:
Proximity Mines: At the end of this tunnel, you'll find some Proximity Mines.

Now enter the door near your starting point. Enter the silver door nearby.
This is an elevator. Take it to a room where a couple of men sit around a
table. Sedate them and take the suitcase in the corner.

Get back in the elevator and head to the lobby. Head through the double doors
next to the secretary. Objective complete.

2.
Check in equipment

Move down this hall until you see an escalator. Go down it and find the conveyor
belt here. Get out that suitcase and place it on the conveyor belt (by pressing
trigger). This will complete the objective.

3. Subvert security monitoring system

After putting the suitcase on the belt, you'll have 45 seconds to make it
to the security monitoring system. Head through the door near the conveyor
belt, past another escalator into a hallway on the opposite side of that
room. Follow the corridor around until you reach a set of stairs. Ascend
them to find the security room.

Quickly activate the computer terminal here. Disarm the guard carrying the
K7, then kill both agents.

4. Board Air Force One

As
soon as you shut off the security system, the base gets invaded by Trent
Easton's security force. These guys all come strapped with Dragons. There
are a group of such soldiers in the room below. Run down the stairs halfway
to lure them up, then retreat to the back corner of the room, using the column
as cover. Spray the hoards with the K7. When they've all dropped, go downstairs
and head back to the escalator room.

Hidden Item:
DY357 Magnum:
There is a small side-passage on the way back to the lobby. This leads to
an elevator, but don't take it down. Instead, kill the NSA agent here. He'll
drop a Magnum.

When you're back in the escalator room, more of Trent's goons will attack
from across the room. Smoke them with Dragon fire, then head across to the
wooden doors in the right corner. This leads to a series of offices. Turn
on the secondary function of the K7 as you prowl these halls. There is a
proxy mine here that you don't want to trigger.

Kill
guards en route to a hallway with an orange and purple stripe on the floor.
Duck into the office here. Be careful--the proxy mine is near. Take it out
to create a large hole in the wall behind it. Move through the blast hole
and into the office. Activate the switch in the corner of this room to open
the safe.

Perfect objective: Obtain flight plans from safe

Inside the safe, you'll find the Flight Plans. In Special mode, there will
be a Shield here instead.

Continue down the hall until you reach an elevator. Ride it down until you
see the hangar.

Do not get off here, however. The elevator will go one floor up and dump
you into a hallway leading to Air Force One. Once aboard, the mission will
be complete.